2005.11.18(於:東京工科大学)
第 499 回 URSI‑F 会合資料

10km を越える 5GHz 帯移動伝搬特性の検討
Frequency Scaling for Path Loss Estimation of 5-GHz Band Around 10-km Distance佐藤 明雄(東京工科大学)， 北 直樹(NTT)， 糸川 喜代彦(NTT 東日本), 渡辺 浩伸(NTT‑AT)，
森 大典(NTT‑AT)

1. INTRODUCTION
Active studies on mobile propagation characteristics in the 5-GHz band are continuing in Japan. This band isdesignated for use by broadband mobile systems such as high-speed wireless access and next generation mobile
systems. For the use of high-speed wireless access systems, measurements up to several kilometers were carriedout in urban and suburban areas around Tokyo [1]. Results of these measurements have contributed to thedevelopment of recommendation ITU-R P.1411 titled “Propagation data and prediction methods for the planningof short-range outdoor radiocommunication systems and radio local area networks”[2]. On the other hand, inrecommendation P.1546, a method for point-to-area predictions for terrestrial services in the frequency range 30
MHz to 3 GHz, is expected to extend the frequency band above 3 GHz [3]. Five-GHz band propagation datameasured at a distance of greater than 10 km will be useful to develop this recommendation.
This paper presents results of measurements carried out at distances ranging from approximately 5 to 30 km. In
these measurements, frequencies in the 2 GHz and 5 GHz bands are used simultaneously. The results enable us toestimate the path loss for the 5-GHz band from that of the 2-GHz band.

2. MEASUREMENT OF PATH LOSS CHARACTERISTICS FOR DISTANT AREA

in
Sh

In order to measure the path loss in an area distant from the transmission point, three sets of measurements
were carried out around Tokyo. The paths are indicated in Fig. 1 by arrows. The starting point of the arrow
indicates the transmission point and the direction of the arrow represents the direction of the antenna at this point.
Table I gives details regarding the transmission stations. The Shinjuku-Kawagoe measurement area is an urban
area that changes to a suburban area. The distance range for the measurement is from 4 km to approximately 30
km. In this case, the transmission antennas were placed on the rooftop of the Mitsui building, which is one of the
200-m skyscrapers in the west Shinjuku area. The propagation environment is considered to be urban tosuburban in the northwest part of the central Tokyo. Hilly terrain with a height variation of 20 m to 50 m persists
into the Kawagoe area. The Shiroyama-Jujo measurement area is a suburban area that changes into an urban area.
The measurement range is from 20 km to approximately 50 km and the transmission antenna was placed on top of
an approximately 600-m high mountain. There is a microwave relay station at the top of the mountain and weused this antenna platform to establish both the transmission equipment and antennas for 2.2 GHz and 5.2 GHz.
The average ground level at the measurement point gradually drops from approximately 70 m to 20 m in the 20
km to 50 km range. Most of the area in the Karagasaki-Chofu measurement is considered to be urban. The
distance range of measurement is 1 to 10 km andthe transmission antenna height is 30 m from theground. The transmission antenna was placed on
the rooftop of the Karagasaki building, which isused for a microwave relay station. The 2.2-GHz
Urawatransmission antenna is a six-element Yagi antenna
with the gain of 12 dBi, and a pyramidal hornantenna was used for the 5.2-GHz transmission
antenna with the gain of 20 dBi. Whentransmitting from Shiroyama, a 32-dBi gainjoo Juparabola antenna was used for the 5-GHz band.
ma t
oya
ir
Tokyo
h
S
The transmitter power for the 2.2 GHz and 5.2
GHz antennas was 30 dBm in the three cases.
Karag
The mobile terminal received a carrier wave
To C as aki
h o fu(CW) at the frequency of 5.2 GHz and 2.2 GHz.
The antenna is a vertical polarized dual band
10km
antenna with the gain of 2 dBi [1]. The antennaheight of the mobile terminal was set to 2.2 m or 3.8 m
Fig. 1 (a) Three paths for path-loss
above ground.
t
ut
ju k

o

g
wa
Ka

oe

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2005.11.18(於:東京工科大学)
第 499 回 URSI‑F 会合資料
Because it is practically impossible to measure all locations in the transmission antenna coverage area, weselected several areas or courses according to the distance from the transmission point. In the Shinjuku-Kawagoe
measurement, each measurement area is relatively large. The length of the measurement course is several
hundred meters to approximately one kilometer. The measurement vehicle moves along a selected course or in anarea to obtain a set of data. In both the Shiroyama-Jujo and Karagasaki-Chofu measurements, the measurement
area was about 100 m ×100 m-square to 200 m×200 m-square for each distance.
[m]

[m]

Shinjuku to Kawagoe

Shiroyama to Jujo[m]

Karagasaki to Chofu
Fig.1(b) Path profiles for the threemeasurements

Table I. Transmission Stations
Transmission station
Height above sea level [m]Range of measurement area [km]Average ground level of measurement
area [m above sea level]

Shinjuku
232
4 to 30
15 to 45

Shiroyama
683
20 to 45
20 to 70

Karagasaki
62
1 to 1030 to 45

3. MEASUREMENT RESULTS(a) Shinjuku-Kawagoe Measurement
Figure 2 shows the distance dependency of the path loss in the 2-GHz and 5-GHz bands obtained in the
Shinjuku-Kawagoe case. The measured data are median values of the path loss at 100-m intervals.
Approximately 2×104 data points were obtained in a 100-m interval when the vehicle speed was assumed to be
18 km/hr because the sampling speed of data recorder was 1 kHz. Red circles and blue triangles correspond to 2.2
GHz and 5.2 GHz, respectively. The free space path loss (FSL) and calculated values by using the Okumura-Hata
equation are plotted as references. Around the 10 km and 20 km points, the path loss decreases locally. These
decreases may be caused by a line-of-sight (LOS) condition that occurred at a high elevation point such as whencrossing a bridge over a road or railway. Except for these low loss locations, most of the path loss values along
the measurement course exhibited an approximate 30 dB decrease compared to the free space path loss values inboth the 2.2-GHz and 5.2-GHz cases. The measured results indicate that the path losses of these frequencies
decrease similarly with distance and a greater than 30-dB path loss (difference between the free space path loss
and measured path loss) is observed. However, occasionally a sudden path loss decrease occurs depending on theoccurrence of the LOS condition.
Figure 3 shows an example of the distance dependency in a short period of 500 m. The figure shows a2

2005.11.18(於:東京工科大学)
第 499 回 URSI‑F 会合資料
comparison of the variation between 100-m median values and 10-m median values. It is obvious that the 10-m
median values fluctuate significantly, which causes a large standard deviation in the path loss values.
In order to study the statistical relationship between the two values, a correlation characteristic, sometimes
expressed by a scatter gram, is useful. Figure 4 is a correlation between the median values of the path loss at 2.2
GHz and 5.2 GHz derived from 100-m median values. In a low path loss region such as below 150 dB, thedifference in path loss is approximately 7 dB. In a higher path loss region such as over 150 dB, the difference inpath loss increases gradually up to approximately 8.5 dB. Figure 5 is also shows the correlation derived from
10-m median values. Since the scattering pattern has a large width compared to that in Fig. 4 because of the larger
standard deviation in the variation of the loss, the path loss dependency of the difference in the two losses of thetwo frequencies is not very clear.
120

130

2.2GHz
5.2GHz

140
150
160

10m-median at 2.2GHz
10m-median at 5.2FGz
100m-median at 2.2GHz
100m-median at 5.2GHz

135
Path loss [dB]Path loss [km]130

F.S.L.

Okumura-Hata

170

140
145
150
155

100m-median value
180

4

5

6

7 8 9 10Distance [km]

20

160
10

30

y = 6.495 + 1.0067x R= 0.95504

y = 1.9457 + 1.037x R= 0.97182
180

170

170

Path loss at 5.2GHz [dB]

180

160
150
140

160
150
140
130

130

10m-median value

100m-median value
120
120

10.5

Fig. 3 Example of path loss variations ina short period

Fig. 2 Path loss vs. distance in Shinjuku-Kawagoe
measurement

Path loss at 5.2GHz [dB]

10.1
10.2
10.3
10.4
Propagation distance [m]130 140 150 160 170
Path loss at 2.2GHz [dB]180

Fig. 4 Path loss correlation between 2.2 GHz and
5.2 GHz in Shinjuku-Kawagoe measurement
obtained from 100-m median value

120
120

130

140 150 160 170
Path loss at 2.2GHz [dB]180

Fig. 5 Path loss correlation between 2.2 GHz and
5.2 GHz in Shinjuku-Kawagoe measurement
obtained from 10-m median value

For further analysis of the statistical characteristics of the difference in path loss between the two frequencies,
the cumulative probability of the difference in the path loss is investigated. Figure 6 shows two cumulative
probabilities of the difference in path loss covering the whole distance range. The median value of the 100-m
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2005.11.18(於:東京工科大学)
第 499 回 URSI‑F 会合資料
interval path loss median values is 7.57 dB and the standard deviation is 1.8 dB. In Fig. 7, the median value of the
10-m period path loss median values is 7.51 dB and the standard deviation is 2.15 dB.
y = 7.6663 + 1.7786norm(x) R= 0.98853
y = 7.5182 + 2.1472norm(x) R= 0.99894

Cumulative probability [%]99.999
99.99
99.9

100m
10m

99
95
90
80
70
50
30
20
10
5
1
.1
.01
.001

Fig.6 Cumulative probabilities of the difference in pathloss between 2.2 GHz and 5.2 GHz
-5

0
5
10
15
Path loss difference [dB]20

Figure 8 shows the cumulative probabilities for different measurement ranges such as 10 km < d < 20 km and
20 km < d. The median in the measurement region is slightly larger than that within 20 km. Figure 8 shows thesame tendency, but for 100-m median values. The results of the median values and standard deviations are
summarized in Table II in addition to the results obtained in the other two measurement cases.
y = 7.285 + 2.0963norm(x) R= 0.99927
y = 7.7964 + 2.1925norm(x) R= 0.99843

99
95
90
80
70
50
30
20
10
5
1
.1
.01
.001

99.99
99.9

10<d<20km
20km<dCumulative probability [%]Cumulative probability [%]99.99999.99
99.9

10m-median value
-5

0

5
10
15
Path loss difference [dB]y = 7.4692 + 1.7236norm(x) R= 0.99607
y = 7.92 + 1.8224norm(x) R= 0.97779

99
95
90
80
70
50
30
20
10
5
1
.1
.01

20

Fig. 7 Cumulative probabilities of thedifference in path loss between 2.2 GHz and
5.2 GHz in case of 10-m median value

10<d<20km
20km<d100m-median value
-5

0
5
10
15
Path loss difference [dB]20

Fig. 8 Cumulative probabilities of the differencein path loss between 2.2 GHz and 5.2 GHz in caseof 100-m median value(b) Shiroyama-Jujo Measurement
In the Shiroyama-Jujo measurement, a distance of nearly 50 km was achieved by transmitting from themountaintop. We established measurement areas in 5 km intervals from 20 km to 45 km distance from thetransmission point. Figure 9 shows the distance dependency of the path loss for 2.2 GHz and 5.2 GHz. Free spacepath loss and calculated results of the Okumura-Hata equation are also plotted. At this distance range, thecalculated loss of the Okumura-Hata equation increases in curvature and is not straight in a log scale with respect42005.11.18(於:東京工科大学)
第 499 回 URSI‑F 会合資料
120
2GHz
5GHz

2.2GHz130
Path loss [km]to the distance. This is because of the correction
for the curvature of the earth’s surface.
However, this curvature tendency is notpronounced in the measured results for the
2.2-GHz and 5.2-GHz bands. Excess loss fromthe free space path loss is kept to approximately
25 dB even at a distance from the transmission
point.

5.2GHzF.S.L.

140
2.2GHz150
160

5.2GHzOkumura
-Hata

170
180

20

30
Distance [km]40

Fig. 9 Path loss vs. distance in Shiroyama-Jujo
measurement

180

Path loss at 5.2GHz [dB]

175
170
165
160
155
150
145

10m-median value
Tx: Shiroyama

140
140 145 150 155 160 165 170 175 180
Path loss at 2.2GHz [dB]Fig.10 Path loss correlation between 2.2 GHz and 5.2
GHz in Shiroyama-Jujo measurement obtained from
10-m median value

y = 9.3042 + 2.7181norm(x) R= 0.98599
y = 8.9046 * e^(0.29983norm(x))
99.99
99.9
10m-median value
Cumulative probability [%]y = 8.4168 + 1.0057x R= 0.8739

R= 0.99719

Tx:Shiroyama

99
95
90
80
70
50
30
20
10
5
1
.1
.01

-5

0
5
10
15
Path loss difference [dB]20

Fig. 11 Cumulative probabilities of thedifference in path loss between 2.2 GHz and 5.2
GHz in case of 10-m median value

Figure 10 is a scatter gram of the path losses at 2.2 GHz and 5.2 GHz. The width of scatter area of the measured
data is larger than that for the Shinjuku-Kawagoe measurement shown in Fig. 6. There is a tendency to shift to alarger loss in the 5.2-GHz band. Figure 11 shows the cumulative probability of the difference in path loss. The
median and standard deviation are 9.05 dB and 2.75 dB, respectively. The median value of the difference in pathloss is larger than that for the Shinjuku-Kawagoe measurement. The distribution shape is not straight in thisnormal distribution graph. It can be said that a lognormal type approximation is suitable when we formulate thismeasured distribution.
(c) Karagasaki-Chofu Measurement
In this measurement, the measurement range is up to 10 km. Since the height of the transmission antenna waslower in comparison to those of other two measurements, the applicable dynamic range was not enough tomeasure the measurement area. However, it is useful to study the frequency scaling in the path loss estimation inan urban area. Figure 12 shows the distance dependency of the path loss for 10-m median values. The free spacepath loss and calculated results by using the Okumura-Hata equation are plotted. The distance between 1 to 2 km
is covered continuously. Other areas at 1 km intervals seems to be separated because the measurement vehicle
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2005.11.18(於:東京工科大学)
第 499 回 URSI‑F 会合資料

Path loss [dB]

moved around selected area of approximately
110
200m ×200m. Since this area is an urban
2.2GHz
5.2GHz120
area, an excess of 25 dB loss is observed over
F.S.L
the measurement range. In the following
2.2GHz130
study of the difference in path loss, the5.2GHz2.2GHzmeasured data within 7 km are used because
140of the lack of the dynamic range inmeasurement area.
150
Figure 13 shows the path loss correlation
between the 2.2 GHz and 5.2 GHz measured
160
5.2GHzdata. A linear shift of the 5.2-GHz path loss
Okumura-Hatavalues from the 2.2-GHz path loss values is170
observed in the 130 to 160 dB range. Figure
10m-median value Tx: Karagasaki
180
14 shows the cumulative probability of the1
10
difference in path loss. A probability
Distance[km]distribution of the measured difference in
Fig. 12 Path loss vs. distance in Karagasaki-Chofu
path loss can be assumed to be a normal
measurement
distribution because a straight line in anormal distribution probability graph canapproximate the data. The median and standard deviation are 8.57 dB and 32.38 dB, respectively.

y = 1.0303 + 1.052x R= 0.97492

Path loss at 5.2GHz [dB]

170
160
150
140
130
120

y = 8.6641 + 2.3814norm(x) R= 0.99741
99.99
99.9

10m-median value
Tx:Karagasaki

110
110 120 130 140 150 160 170 180
Path loss at 2.2GHz [dB]Fig.13 Path loss correlation between 2.2 GHz
and 5.2 GHz in Karagasaki-Chofu measurement
obtained from 10-m median value

Cumulative probability [%]

180

99
95
90
80
70
50
30
20
10
5
10m-median value
Tx: Karagasaki

1
.1
.01

-5

0

5
10
15
Path loss difference [dB]20

Fig. 14 Path loss correlation between 2.2 GHz and
5.2 GHz in Karagasaki-Chofu measurement
obtained from 10-m median value

Table II summarizes the statistical parameters related to the difference in path loss obtained in the threemeasurements. In the free space path loss model, the path loss depends on the frequency and is expressed as
20*log(f). The difference in path loss between 2.2 GHz and 5.2 GHz is 7.47 dB according to the free space pathloss model. In the Shinjuku-Kawagoe measurement, median values of the path loss are distributed from 7.29 to
7.79 dB. It can be said that the difference in path loss in this measurement is similar to that of the free space pathloss. At a distance beyond 20 km, the difference in path loss increases slightly. The Shiroyama-Jujo measurement
was carried out at 20 to 50 km. The largest difference in path loss of 9 dB (median) and 2.75 dB (standard
deviation) were obtained in these three measurements. Otherwise, we had a large median and standard deviation,
8.57 dB and 2.38 dB, within 10 km range for the Karagasaki-Chofu measurement.

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2005.11.18(於:東京工科大学)
第 499 回 URSI‑F 会合資料
Table II. Statistical Parameters Obtained in Three Measurements
Median [dB]
Shinjuku-Kawagoe
7.57
100-m period measurement
10 km < d < 20 km
7.34
20 km < d7.79
Shinjuku-Kawagoe
7.51
10-m period measurement
10 km < d < 20 km
7.29
20 km < d7.76
Shiroyama-Jujo
9.05
10-m period measurement
Karagasaki-Chofu
8.57
10-m period measurement

Standard deviation [dB]
1.80
1.73
1.86
2.15
2.01
2.19
2.75
2.38

We can say that the difference in path loss between the 2-GHz band and the 5-GHz band in a mobile
propagation environment is almost the same as that of the free space path loss model if we had only the
Shinjuku-Kawagoe measurement data. However, the other two measurements indicate that there is somecomplexity to the direct conversion of the path loss in the 2-GHz band to the 5-GHz band. This may indicate thatthe path category such as urban, suburban, and rural should be considered more precisely to derive a conversion
method.

4. CONCLUSION
We carried out three sets of propagation measurements to investigate the difference in path loss between the
2-GHz band and 5-GHz band in order to develop a frequency scaling method to estimate the path loss in the SHF
band. The difference in path loss is approximately 7 to 9 dB based on the analysis of measured data for medianvalues in 10-m intervals. Further data will be necessary to clarify the measurement area especially beyond 20 km
from the transmission point.
REFERENCES[1] N. Kita, S. Uwano, A. Sato and M.Umehira, “A Path Loss Model in Residential Areas Based on Measurement Studies
Using a 5.2-GHz/2.2-GHz Dual Band Antenna”, IEICE Trans. Vol. E84-B, No.3, pp. 368-376 (2001).
[2] Recommendation P.1411, “Propagation data and prediction methods for the planning of short-range outdoor
radiocommunication systems and radio local area networks”, ITU-R Recommendations P-series 2003.
[3] Recommendation P.1546, “Method for point-to-area predictions for terrestrial services in the frequency range 30 MHz to
3 000 MHz”, ITU-R Recommendations P-series 2003.

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